Also, is it possible to have pkgsrc keep several installed package databases?

Definitely. The pkg_install (like pkg_add, pkg_delete) tools honor the
PKG_DBDIR environment variable or the "-K" option to choose the package
database directory. I would suggest using different LOCALBASES for these
packages though.

(Also pkgviews worked for me in the past.)

By the way, I do have access to a fast DragonFly build machine. And have
been committing some "pkgsrc" fixes ...